Determination of the volatile fatty acid content in the rumen liquid: comparison of gas chromatography and capillary isotachophoresis
2009
Filipek, J.,Veterinarni a Farmaceuticka Univ., Brno (Czech Republic). Klinika Chorob Prezvykavcu | Dvorak, R.,Veterinarni a Farmaceuticka Univ., Brno (Czech Republic). Klinika Chorob Prezvykavcu
Two analytical procedures, capillary isotachophoresis (ITP) and gas chromatography (GC), used to determine volatile fatty acids in the rumen liquid were compared. Acetic, propionic, butyric and valeric acids were determined. No significant differences (n = 53) were identified in the amounts of acetic and propionic acids. The results were highly consistent. For butyric acid, GC yielded higher results with a constant error of approximately 0.5 mmol/L in the whole range of concentration. In terms of diagnostics, however, this size of error is non-significant. In the case of valeric acid a proportional error was found. GC yielded higher values, the difference being greater for the low values while for the higher values the results were almost identical. However, valeric acid is a minor acid and its determination is of secondary significance to rumen fermentation assessment. GC is able to clearly differentiate between n and iso forms in the case of butyric and valeric acids. It can be stated that the two analytical methods yield comparable results and both can be used for the needs of practical diagnostics.
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